Gas-blast circuit interrupter with purifying means



Oct. 26 1965 l W. M. LEEDS 3,214,552

GAS-BLAST CIRCUIT INTERRUPTER WITH PURIFYING MEANS Original Filed March27, 1961 ATTORNEY United States Patent O 7 claims. (ci. 20o-14s) This isa division of application Serial No. 98,632, filed March 27, 1961.

This invention relates generally to gas-blast circuit interrupters, and,more particularly, to filtering and purifying means for the arced gaswhich is used to effect interru-ption of the established arcing.

A general object of the present invention is to provide an improvedcompressed-gas circuit interrupter of the type employing as anarc-extinguishing medium a gas of relatively high dielectric strengthand an efficient arc extinguisher, such as sulfur-hexafiuoride (SP6)gas, selenium-hexauoride (SeFG) gas, (CF3SF5), and other gases which mayhave active products of decomposition following their use asarc-extinguishing gases.

A more specific object of the present invention is to provide animproved compressed-gas circuit interrupter utilizing a substantiallyclosed gaseous system in which the gas is repeatedly reused, and inwhich novel filtering means are provided to purify the gas -prior to itssubsequent ejection into the general interior of the circuitbreakerstructure.

Power circuit breakers using SP6 gas, for example, for insulation andarc interruping have been built in many forms: single-bushing types,live-tank types, deadtank types, etc., all showing excellent performancepossibilities. By proper choice of insulating materials, deteriorationfrom the effects of active gas products of arcing has been avoided, withcontainers of activated alumina powder being provided to graduallypurify the gas. Metallic fiuoride powders are also formed by arcing atthe contacts in SFS, but there are insulating when dry and normally giveno trouble.

Carbon particles .from gases such as GF4 and C3138 l should also beremoved to prevent their deposit upon insulating surfaces.

However, maintenance of breakers may involve exposure of personnel toslightly toxic vapors, if breakers are opened immediately after heavyfault interruptions. Also, on humid days, the fluoride powders absorbmoisture quickly, and very complete cleaning of all insulating surfacesbecomes essential.

The present invention is intended to eliminate such maintenancedifficulties by directing all arced gases into a metal chamber where noinsulation stressed by voltage would be present. Then an activatedalumina powder filter or a mesh filter is provided, through which thegas must flow before it can reach insulating surfaces. Thus, reactivevapors and powders are removed before the gas is returned to the rest ofthe breaker for reuse.

Since the integrity of the insulation to ground is of paramountimportance, fairly inaccessible parts such as rods, tubing and porcelainsurfaces in the supporting columns of the breaker are particularlyimportant to protect from fluoride powder accumulation. This means3,214,552 Patented Get. 26, 1965 that the screening action of the filterin taking out solid particles as its primary function. If purificationof the gas is not complete in this filter just below the interrupter,additional purification will take place in the filter provided ahead ofthe compressor used to fill the highpressure gas reservoir.

Effective interrupting action requires a high velocity gas flow throughthe downstream valve to low pressure. Excessive restriction of the flowpassages, for instance by too much pressure drop in a large filter closeto the valve, could build up undesirable back pressure. This situationis avoided by providing an expansion volume below the valve ahead of thefilter and by limiting the filter function primary to a powder screeningaction with relatively small pressure drop.

Accordingly, it is a further object of the present invention to provideimproved compressed-gas circuit-breaker structures, in which maintenanceproblems are reduced by collecting all of the arced gas following itsuse as an arc extinguisher, and immediately purifying, or filtering sucharced gas prior to its subsequent release into the general interior ofthe breaker structure.

Further objects and advantages will readily become apparent upon readingthe following specification, taken in conjunction with the drawingillustrating a vertical sectional view taken through a compressed-gascircuit interrupter, the contact structure being illustrated in thepartially open-circuit position.

The figure, as illustrated, shows a type of circuitinterruptingstructure embodying the principles of the present invention. It will benoted that there is provided a live metallic tank 42 filled withhigh-pressure gas, for example suliur-hexaiuoride (SP6) gas at 150p.s.i. Extending laterally through the live metallic highpressure tank42 is a pair of oppositely-disposed terminal bushings 43, 44, supportingrelatively stationary contact posts 45 within the general interior 46 ofthe tank structure 42. The terminal bushings 43,44 preferably compriseinsulating weatherproof casings 47 and outer terminal cap portions 48,49.

Cooperable with the inner ends of the relatively stationary contactposts 45 is a substantially U-shaped bridging structure, generallydesignated by the reference numeral 50, and comprising a pair ofvertically-extending conducting operating rods 51, interconnectedadjacent their lower ends by a conducting transverse bridging member 52.An insulating operating rod 53 extends interiorly of an upstandingsupporting insulating column 54, and serves to effect upward closing anddownward opening movement of the pair of conducting operating rods 51 inan obvious manner.

It is desirable to effect a sealed connection between the operating rod51 and the wall of the live tank 42. For this purpose, preferablymetallic bellows 55 are provided, being sealed, as by a brazedconnection to the tank 42, and also being sealed, as by a brazedconnection, to a plate 56, which, in turn, is afiixed to the conductingoperating rod 51 and movable therewith.

`Disposed interiorly of the live tank structure 42 is a blast valvehousing chamber 57 having a pair of orice openings 58 associatedtherewith. A movable blast valve 59 has a pivotal linkage 60 engaged bya drive-pin 61, affixed to, land movable with, the left-hand conductingrod 51, as viewed in the ligure. The blast valve 59 is guided by amoving guid-e 62 slidable within a guide housing 63 affixed by a pair ofsupports 64 to the blast valve housi'ng 57. As shown, -a compressionspring 65 biases lthe guide 62, and consequently the blast valve 59 tothe closed position.

vIn the closed-circuit position of the circuit interrupter `66, theelectrical circuit passing therethrough generally includes line-terminal connectioln 48, relatively stationary contact post 45, fingercontacts 67, conducting operating rod 51, conducting transverse member52, right-hand conducting operating rod 51, right-halnd relativelymovable contact fing-er 67, right-hand contact post 45, from whence thecircuit extends through the right-hand terminal bushing 44 to the otherterminal connection 49.

During the -openihg operation, sui-table means, not shown, is operable-to effect downward opening movement of the insulating operating rod 53.This will bring about corresponding downward opening movement of thetrainsverse conducting member 52, and consequently the conductingoperating rods 51, which are secured thereto.

The downward opening moveme'nt of the conducting operating rods 51 willeffect separation between the mov- -able contact `fingers 67 and theinner extremities of the contact posts 45 to draw arcs therebetween.Preferably, one of the contact lingers 67a is made slightly longer thalnthe other contact finger 67, and has an arc-resisting tip portion 68associated therewith. A

Simultaneously with the Vdownward opening movement of the left-handconducting operating rod 51, the drivepin 61 associated therewitheffects, through the linkage 60 upward opening movement of the blastvalve 59 to permit a blast of gas to pass out of the valve housing 57and into a metallic exhaust chamber `69. Filtering material, such asfine wire mesh and activated lalumina 70 `is preferably disposed withinthe exhaust cylinder 69, and this forces all of the exhaust gases topass therethrough prior to subseque'nt passage through perforations 71and into the general interior 72 within the upstanding insulating column54. The sulfur-hexafluoride gas within the insulating column 54 ispreferably at a pressure of substantially 30 p.s.i.

The opening of the blast valve 59, -dowlnstream of the orifice opening58, will cause the radially inflowing blast of gas about the station-arycontact post 45 to carry the are 73 to an arcing-horn portion 74, whichconstitutes a portion of the guide cylinder 63. As shown in the figure,the two serially related arcs 73, ex-telnding through the orificeopenings 58, are subjected to a radial inward blasting of gas, whichpasses downwardly within the valve housing 57 and is exhausted into thelower exhaust chamber 69. It will be observed that all of the arced gasis compelled to pass through `the metallic exhaust chamber 69, andthrough the filtering material 70 prior to its subsequent reuse.

Suitable compressor means, not shown, are operable to extract the gaswithin the general ilnterior 72 of the insulating column 54, which issubstantially at 30 p.s.i., and to recompress this gas to thehigh-pressure value of 150 p.s.i., from whence it is fed from thecompressor upwardly by way of the feed tube 75 from ground potential andback into the upper live tank 42 for subsequent reuse.

From the foregoing discription of the circuit interrupter 66, it will beapparent that all of the gas used duri'ng interruption of the arcs 73will be compelled to pass through the filtering material 70 prior to itssubsequent reuse.

From the foregoing, it will be apparent that in the circuit interruptery66, illustrated in -the drawing, that there is provided a novelconstruction with a high-pressure reservoir 42 at high potential, withterminal bushings 43, 44 at each side of the tank. Pulli'ng open thecontacts 67 operates a blast valve 59 on the exhaust side of the flowchannels 58. The exhaust gases go through the filter 70 in the metalexhaust chamber 69 and finally into the supporting porcelain column 54.The low-pressure gas from the column 54 is recompressed and fed up aninsulating pipe `75 to the high-potential high-pressure tank 42.

The volume just below the blast valve 59 aheadof the filter 7th allowsfree flow and gas expansion for improved interrupting action, limitingthe back-pressure build-up that would result from locating the filter 70very close to the valve 59 without this expansion volume.

Although considerable laboratory data is available in regard -to thereaction of SFS, by reason of analogy, it is believed that the samecontaminating problem is present with gases such as SeF6, CF3SF5 andSO2F2.

The filters set forth in the above described circuit interrupter may beemployed to remove carbon from certain gases, which give off carbon`during circuit interruption. A few of such gases are CSFB, the Freongases, such as Freon l2 and GF4. For the purpose of removing carbon,glass wool, paper, such as blotting paper, may be employed. By reason ofsuch filtering of the carbonemitting gases, such gases will be in acondition for subsequent reuse without the deleterious eff-ect of carbonbeing deposited upon insulating surfaces.

From the foregoing description, it will be apparent that the inventionis particularly colncerned with a gas-type of circuit interruptercomprising a closed gaseous system, wherein arced gas is collected andfiltered, before being released to come into contact with high-voltageinsulation.

Although there have been illustrated and described a specificinterrupting structure, it is to be clearly understood that the same wasmerely for the purpose of illustratidn, and that changes andmodifications will readily be made therein by those skilled in the art,without departing from the spirit and scope of the invention.

I claim as my invention:

1. The combination in a gas-blast circuit interrupter of a high-pressurechamber, said interrupter utilizing a gas which when exposed to arcilngforms reactive products of decomposition at least momentarily, separablecontact means disposed at least partially within said high-pressurechamber for establishing an arc within the highpressure chamber, meansdefining a downstream blast valve at high potential separate from saidcontact means, the opening of said downstream blast valve causing ahighpressure flow of gas adjacent said arc and through the blast valve,a metallic filter exhaust chamber at high potential disposed downstreamof said blast valve for filtering all of the arced gas flowing throughthe blast valve, means defining insulating surfaces subject to voltagepotential on the exhaust side of said downstream blast valve and servingas a conduit for arced gas, and the metallic filter exhaust chambercontaining a suitable fil-ter material so as to effect immediateextraction of said reactive products from the arced gas prior torecirculation of the arced gas against said insulating surfaces.

2.'A high-voltage compressed-gas circuit breaker including a livemetallic tank filled with gas under pressure, said interrupter utilizinga gas which when exposed to arcilng forms reactive products ofdecomposition at least momentarily, a supporting insulating column forsupporting said live metallic tank an adequate distance :above ground,said insulating column `defining insulating surfaces subject to voltagepotefntial on the exhaust side of said downstream blast valve Iandserving as a conduit for arced gas, and the metallic filter exhaustchamber containing a suitable filter material so `as to effect immediateextraction of said reactive products from the arced gas prior torecirculation of the arced gas against said insulating surfaces, a pairof terminal bushings protruding into said live metallic tahk andsupporting relatively stationary contacts therein, movable bridgingcontact means for electrically bridging .the pair of relativelystationary contacts in the closed-circuit position, orifice meansassociated with each relatively stationary contact, means defining adownstream blast valve which when [opened will cause a blast of gas fromwithin the live highpressure tank through the pair of orifice means andthrough the downstream blast valve, and a metallic filter exhaustchamber disposed downstream of said blast valve for collectingsubstantially all of the arced gas and iiltering the same prior tosubsequent reuse.

3. A high-voltage compressed-gas circuit breaker including a livemetallic tank iilled with gas u'nder pressure, a supporting insulatingcolumn for supporting said live metallic tank an .adequate distanceabove ground, a pair of terminal bushings protruding into said livemetallic tank and supporting relatively stationary contacts therein,movable bridging contact means for electrically bridging the pair ofrelatively station-ary contacts in the closed circuit posi-tion, oricemeans associated with each relatively stationary contact, means defininga downstream blast valve which when opened will cause a blast of gasfrom within .the live high-pressure tank through the pair of oriticemeans and through the downstream blast valve, and a metallic filterexhaust chamber disposed downstream of said blast valve and at leastpartially within said supporting insulating column for collectingsubstantially all of the arced gas and ltering the same prior tosubsequent reuse.

4. A high-voltage compressed-gas circuit breaker including -a livemetallic tank filled with gas under pressure, a supporting insulatingcolumn for supporting said live metallic tank -an adequate distanceabove ground, a pair of terminal bushings protruding into said livemetallic tank and supporting relatively stationary contacts Itherein,movable bridging contact means for electrically bridging the pair ofrelatively stationary contacts in the closed circuit position, saidmovable bridging contact means including a substantially U-shapedconducting structure, insulating rod means extending through saidsupporting insulating column for actuating said U-shaped conductingstructure, orifice means associated with each relatively stationarycontact, means dening a downstream blast valve which when opened willcause a blast of gas from within the live high-pressure tank through thepair of oriiice mealns and through the downstream blast valve, Iand lametallic filter exhaust chamber disposed downstream lof said blast valvefor collecting all of the arced gas and iiltering the same prior tosubsequent reuse.

5. A high-voltage compressed-gas circuit breaker including a livemetallic tank filled with gas under pressure, a supporting insulatingcolumn for supporting said live metallic tank an adequate idistariceabove ground, a pair of terminal bushings protruding into said livemetallic tank and supporting relatively stationary contacts thereon,movable bridging contact means for electrically bridging the pair ofrelatively stationary cointacts in the closed circuit position, saidmovable bridging contact means including `a substantially U-shapedconducting structure, insulating rod means extending through saidsupporting iiisula-ting column for actuating said U-shaped conductingstructure, a blast valve housing having a pair of orifice openings sothat an orifice opening is associated with each relatively stationarycontact, means ldefining a downstream blast valve associated with saidvalve housing, which when opened will cause a blast -of gas from withinthe live high-pressure tank through the pair of loriiice openings .andthrough the :downstream blast valve, and a metallic iilter exhaustchamber disposed downstream of said blast valve for collectingsubstantially all of the arced gas and filtering the same prior tosubsequent reuse.

6. A high-voltage compressed-gas circuit breaker including a livemetallic tank filled with gas under pressure, a supporting insulatingcolumn for supporting said live metallic tank an adequate distance aboveground potential, a pair of terminal bushings protruding into said livesmetallic tank and supporting relatively stationary contacts therein,movable bridging contact means for electrically bridging the pair ofrelatively stationary contacts in the c-losed-circuit position, 'saidmovable bridging contact means including a substantially U-shapedconducting structure, insulating rod means extending through saidsupporting insulating column for actuating said -Ushaped conductingstructure a blast valve housing having a pair of oriiice openings sothat an oriilce opening is associated with each relatively stationarycontact, means dening a down-stream blast valve associated with saidvalve housing, which when opened will cause a blast of gas from withinthe live high-pressure tank through the pair of orifice openings andthrough the downstream blast valve, a metallic iilter exhaust chamberdisposed downstream of said lblast valve for collecting all of the aeredgas and purifying the same prior to subsequent reuse, and said metallic-iilter exhaust chamber being positioned between the rod portions of thesubstantially U-shaped conducting structure and at least partiallywithin the upper end of said supporting insulating column.

7. A high-voltage compressed-gas circuit breaker including a livemetallic tank filled with gas under pressure, an upstanding supportinginsulating column for supporting said live metallic tank an adequatedistance above ground potential, a pair of terminal bushings protrudinglaterally into said live metallic tank and supporting relativelystationary contact posts therein, movable bridging contact means forelectrically bridging the pair of relatively stationary contact posts inthe closed circuit position of the interrupter, said movable bridgingcontact means including a substantially IU-shaped conducting lstructurecomprising vertically extending conducting operating rods and a lowerbridging conducting transverse connecting portion, said verticallyextending conducting operating rods extending through t-he wall of saidmetallic tank, insulating rod means extending through said upstandingsupporting insulating column for actuating said transverse conductingportion, sealing means disposed between each of the vertically extendingconducting rod portions of the U-shaped bridging structure and the wallof the live metallic tank, a blast valve housing having a pair of oriceopenings, an orifice opening associated with each relatively stationarycontact post, means defining a downstream blast valve supported by saidvalve housing, which when opened will cause a blast of gas from withinthe live high-pressure tank through the pair of orifice openings andthrough the downstream blast valve, and `a metallic filter exhaustchamber disposed downstream of said blast valve for collectingsubstantially all of the arced gas purifying the same prior tosubsequent reuse.

References Cited by the Examiner UNITED STATES PATENTS 2,108,560 2/ 38Kesselring 200-148 2,125,525 8/38 Thommen 20G-148 2,221,720 11/40 Prince200-148 2,459,600 1/49 Strom 200-148 2,748,226 5/56 MacNeill et al.240-148 2,757,261 7/56 Lingal et al. 200--148 2,824,937 2/58 Strom200-148 2,955,182 lO/60 Caswell et al. 200-148 2,979,591 4/61 Friedrich200-150 3,009,042 11/61 Schrameck et al. 200--148 FOREIGN PATENTS874,045 4/ 42 France., 1,136,382 12/56 France. 1,222,392 1/ 60 France.

401,332 11/ 33 Great Britain.

KATI-ILEEN H. CLAFFY, Primary Examiner.

ROBERT K. SCHAEFER, BERNARD A GILHEANY,

Examiners.

1. THE COMBINATION IN A GAS-BLAST CIRCUIT INTERRUPTER OF A HIGH-PRESSURECHAMBER, SAID INTERRUPTER UTILIZING A GAS WHICH WHEN EXPOSED TO ARCINGFORMS REACTIVE PRODUCTS OF DECOMPOSITION AT LEAST MOMENTARILY, SEPARABLECONTACT MEANS DISPOSED AT LEAST PARTIALLY WITHIN SAID HIGH-PRESSURECHAMBER FOR ESTABLISHING AN ARC WITHIN THE HIGHPRESSURE CHAMBER, MEANSDEFINING A DOWNSTREAM BLAST VALVE AT HIGH POTENTIAL SEPARATE FROM SAIDCONTACT MEANS, THE OPENING OF SAID DOWNSTREAM BLAST VALVE CAUSING AHIGHPRESSURE FLOW OF GAS ADJACENT SAID ARC AND THROUGH THE BLAST VALVE,A METALLIC FILTER EXHAUST CHAMBER AT HIGH POTENTIAL DISPOSED DOWNSTREAMOF SAID BLAST VALVE FOR FILTERING ALL OF THE ARCED GAS FLOWING THROUGHTHE BLAST VALVE, MEANS DEFINING INSULATING SURFACES SUBJECT TO VOLTAGEPOTENTIAL ON THE EXHAUST SIDE OF SAID DOWNSTREAM BLAST VALVE AND SERVINGAS A CONDUIT FOR ARCED GAS, AND THE METALLIC FILTER EXHAUST CHAMBERCONTAINING A SUITABLE FILTER MATERIAL SO AS TO EFFECT IMMEDIATEEXTRACTION OF SAID REACTIVE PRODUCTS FROM THE ARCED GAS PRIOR TORECIRCULATION OF THE ARCED GAS AGAINST SAID INSULATING SURFACES.